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# Log Help watch

1. I'm stuck on this question and was wondering if anybody could provide some help.

3) Log2x=8+9logx2

I followed through my text book working and got an answer of 59049 instead of 0.5,512. Any help would be greatly appreciated ty
2. Could you make it clear what the bases are, is it to the base 10? x? 2?
3. (Original post by CapsLocke)
Could you make it clear what the bases are, is it to the base 10? x? 2?
My guess

but of course there are other possibilities.
4. (Original post by steve2005)
My guess

but of course there are other possibilities.
You're right bro,
5. You could start by changing the log-to-base-x into a log-to base-2
6. This is my working:

log2x=8+9logx2
log2x=8+9/log2x

-Let log2x = y

y=8+9/y
(x y)
y^2=8y+9
y^2-8y-9=0
(y+1)(y-9)
Y=-1 or 9

Log2x=9
x=9^2
81

or

1

whats wrong?
7. If log-to-base-2 (x) = 9
x = 2^9
8. (Original post by ian.slater)
If log-to-base-2 (x) = 9
x = 2^9
cheers bro
9. Not easy to put maths formulae. So I wrote the solution on a paper and uploaded the picture.
Attached Images

10. You almost got the correct answer. log2 y=9 then y=2^9=512

(Original post by joestevens2092)
This is my working:

log2x=8+9logx2
log2x=8+9/log2x

-Let log2x = y

y=8+9/y
(x y)
y^2=8y+9
y^2-8y-9=0
(y+1)(y-9)
Y=-1 or 9

Log2x=9
x=9^2
81

or

1

whats wrong?

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